In a shunt-based current measurement apparatus, the current is measured by inserting a known low resistance “shunt” in series with the current to be measured, and then measuring a voltage dropped across the series shunt. Application of Ohm's Law (current (I)=voltage (V)/resistance (R)) will yield the current flowing through the shunt. The accuracy of the current measurement can depend on the accuracy of the voltage measurement and the accuracy of the resistance of the shunt itself.
Typically, the system is factory calibrated, which can include temperature compensation over a number of temperature points to compensate for temperature effects of the shunt. For automotive applications, a single temperature calibration is often used. However, over the lifetime use of the shunt, its value can change independent of temperature and this can be unpredictable. Moreover, in the typical application, the current through the shunt is monitored continuously, and this can present challenges for monitoring the shunt itself. The shunt typically has less a resistance of less than one Ohm, which can add further challenges.